DESCRIPTION: The applicant hopes to increase understanding of the Hh and Wg signaling pathways by elucidating mechanisms about how the known components work and will identify new components in these pathways. Aim 1 will test the proposed model for Hh signaling, will map the domain of Smoothened that confers sensitivity to Ptc, and will test specificity of activating downstream components. Aim 2 will test the specific hypothesis that the serpentine receptors activate heterotrimeric G proteins. Aim 3 will use an elegant genetic screen to identify new genes in the Wg signaling pathway.